Process for mining sulphur



Patented Dec. 28, 1926.

UNITED STATES PATENT OFFICE.

WILSON T. LUNDY AND HOIEB S. BUBNS, OI FREEPOBT, TEXAS, ASSIGNORS TOFREE- PORT SULPHUR COMPANY, OF FREEPORT, TEXAS, A CQBPORATION OF TEXAS.

; rnocnss ron Emma sutrnunp llo brewing.

Ourinvention relates to the process of recovery of elemental sulphur from sulphur bearing deposits by means of what is commonly known as the hot-water method, It

has for its object the. better control of the movement of the fluid heating medium (commonly water)' used in this process. p

-In order that the operation of our invention may be made clear we will first describe the nature of the sulphur bearing formations commonly encountered in the United States and'will alsobriefiy describe the socalled hot-water method as now generally applied to sulphur mining.

By far the greater part of the sulphur known to/exist inthe elemental form on the American Continent occurs in the form of pure crystals of elemental sulphur interspersed with gypsum or lime rock or mixtures of these rocks.- It occurs usually in what are knownas domes, which are found in considerable numbers along the coastal plane, bordering on the Gulf of 8 Mexico inthe States of Texas and Louisiana. The sulphur bearing portion of these domes, or of such of them as are known to contain sulphur. lies at depths varying from a few hundred feet-up to 1500 or 2000 feet.

The-sulphur-bearinq portions of these dome formations are usually more or less porous or spongy They contain cavities of widely varying sizes, 7

of verv great size, which may be aptly de- 1 scribed as caverns. These cavities are more or less inter-connected by channels through which water/may circulate with a greater or less degree number and slzes both of the 'cavlties or pores, and of the inter-connecting channels.

Being. at considerable .depth in the ground tion. 1 This permeabilityjs a function of and V is afiected hvtwo variables. One variable is the size cavities in the'sulphur' bearing formation from minute pores to cavities- .of freedom depending upon the there is often to be. found a and number of; thepores or Application filed August 5, 1926. Seriallo. 127,475.

and'the second variable is the number and size of the 1 inter-connecting passages or channels between the cavities. Some of the effects of this difference in permeability will be described later.

The recovery of sulphur from these sulphur bearing formations situated at depths of. several hundred'feet under the surface of the ground is commonly accomplished by what isgenerally known as the hot water process. This process consists essentially in forcing water at a high temperature, usually above 300 F., and under a pressure usually above 100 Ibsper'square inch, into the sulphur bearing formation, and raising to the surface of the ground the sulphur melted by the water.

In the carrying out of this process holes are drilled from the surface of the ground down into and through the sulphur producing horizon; In these holes or wells are placed a series of pipes of various diameters one w1th1n another m such a manner that hot water under the desired pressure and temperature conditions may be forced into the sulphur bearing strata through the water pipes. and also that fluid or melted sulphur may be simultaneously lifted to the surface through one of the inner pipes of the series. The hot water so injected into the sulphur bearing formation moves through the pores and cavities of the formation and while so passing raises the temperature of the formation with which it comes into contact. This rise of temperature continues until those portions of the formation through which quantities of the hot water have passed reach a temperature approximately equ'alto that of'the injected water. As pure sulphur melts at about 240 F., and as the hot water is injected at a considerably higher temperature. there results a melting of the sulphur contained in the formation. This melted sulphur, being much heavier than the water. finds its way downward through the heated portion of the porous formation surrounding the bottom and lower'portion of the pipes and enters the pipes through perforations suitably placed and provided for the purpose. This molten "sulphuris then lifted to the surface of the ground by means of compressed air,.utilizing the well known device known as an air lifts Asalready stated, there is a wide difference between sulphur formations and also between different portions of the same formation as regards the permeability of the formation. In some cases the pores, cavities and passages are relatively small in size and few innumber and uniformly distributed throughout the formation. In other cases these cavities are much more numerous, much larger and unevenly distributed throughout the formation. In some formations it is not uncommon to find very large cavities and very open channels through which the water may pass. In the former case, where the pores, cavities and passages are small and uniformly distributed the water may find its way slowly through the openings and radiate uniformly in all directions from the pipes through which it is injected into the sulphur bearing formation. This is a very desirable condition and results in a relatively complete melting of the sulphur in all directions from the pipes. In the latter case, where the cavities and passages are much larger and irregularly distributed, it is found that the hot water finds a free and easy passage away from the pipes through channels or openings in one or more directions and a relatively obstructed and difficult passage in other directions, the result is that only a relatively small proportion of the sulphur in the vicinity of the'pipes is melted. This often results in large and valuable deposits of sulphur remaining unmelted within easy ,melting radius from the well after production has ceased. We have foundthat this quick and free passage of the melting fluid can be overcome by the use of a hot fluid of greater viscosity than plain water such as is commonly used. This viscous fluid may be prepared by mixing either soluble or insoluble solids or liquids in the water to be used as a heating medium. We have found that we can produce a suitable viscous fluid by making an intimate mixture of water with a solid and relatively insoluble substance as, for example, a very finely precipitated lime such as that produced when hard water is treated with caustic. lime or hydrated lime to precipi tate the dissolved lime from the water. This precipitated lime, comonly called lime sludge, is a waste product of a water treating plant and is of little or no commercial value. In fact, it is usually a difiicult and costly by-product to dispose of. By mixing lime sludge with water in proper proportions we produce a fluid having a relatively high viscosity. This fluid, of relatively' high viscosity, is heated to a suitable temperature above the melting point of sulphur and is injected into the sulphur bearing form'ationin a manner similar in general to that described above.

the passage of the fluid through the cavities and passages of the porous sulphur bear- The increased vis- -cosity of the heating fluid tends to retard ing formation, and so tends ,to more evenly distribute its flow in all directions from the well.

Another important feature of our invention lies in the greater resistance to the migration of the waters naturally occurring in the porous sulphur bearing formations, which is introduced by the pressure of a viscous liquid in the cavities of the formation. The filling of cavities, passages and crevices of an open, porous type of sulphur bearing formation with a viscous liquid, restricts and reduces the freedom of flow of format-ion water, from one portion of the sulphur bearing horizon to another and so lessens the diffusion and dispersion of the heat carried into the formation by the fusing medium. formation water results in greater yield of melted sulphur for a given amount of fusing liquid discharged into the formation.

Still another important characteristic of our invention is the advantage to be gained by injecting our viscous fusion fluid into operating wells so that sulphur mav be continually melted from a gradually increasing area surrounding the well while the molten sulphur is simultaneously being. removed from the bottom of the well to the surface of the ground.

Other and further advantages of our process will appear to one skilled in the art, who applies it to the mining of sulphur.

I'Ve claim as new and novel:

1. The process of; mining sulphur which consists of injecting into the sulphur bearing formation a hot fusing liquid having a viscosity greater than that of water, and recovering the fused sulphur.

2. The-process of mining sulphur which This restricted migration of the consists of injecting into the sulphur bearing 1 4. The process of mining sulphur which consistsof injecting into the sulphur bearing formation a heated mixture of water and a colloidal material in suspension, said mixture having a viscosity greater than that of water, a

and recovering the fused sulphur.

5. The process of mining sulphur which consists of injecting into the sulphur bearing formation a heated mixture of water and precipitated calcium carbonate having a viscosity greater than that of water, and re-.

covering the fused sulphur.

.6. The process of mining sulphur which consists of injecting into'the sulphur bearing formation a heated mixture of water. and

.finely" divided earthy 1 mm having a viscosity lime sludge, said mixture havin a viscosity *greater. than that of water, an recovering the fused sulphur.

7. The process of mining sulphur which 7. consists of in ect1n into the sulphur bearing mixture of water and a material, said mixgreater than that of water, and recovering the fusedsulphur.

8. The process of mining sulphur which consists of injecting into the sulphur bearing formation a heated mixture of water and formation a heate colloidal clay, said mixture having a visthat of water, and recovering the fused sulphur.

10. The process of mining sulphur which consists of injecting into the sulphur bearin formation a-heated mixture of lime sludge and water, containing not less than by weight of lime sludge and having a viscosity greater than that of Water, and recovering the fused sulphur.

11. The. process of mining sulphur which consists of injecting into the sulphur bearing formation a heate mixture of lime sludge and water, containing not less than by weight of lime sludge and havin a viscosity greater than that of water, an recovering thefused sulphur.

' 12. The process of mining sulphur which consists of injecting into the sulphur bearing formation a heated fusing fluid consisting of a colloidal sus ension of earthy materials in water,said uid having a viscosity greater than that of Water; and recovering the fused sulphur.

13. The process of mining sulphur which consists of injecting into the sulphur bearing formation a hot fusion liquid havin a viscosity greater than that of water, an simultaneously recovering the fused sulphur.

Signed at Freeport, in the county of Brazoria, and State of Texas, this 19th day of July, A. D., 1926. v

' WILSON T. LUNDY..

HOMER S. BURNS. 

